If you don't have working "built-in" Ethernet (or your computer has no Ethernet at all) and do not have a supported PCIe WiFi card, then chances are you're using USB WiFi for internet access. The problem, of course, is that you have no access to the Mac App Store in that scenario.
On a whim, I created NullEthernet.kext to solve this problem. It is a "fake" Ethernet kext that will never actually work. That is, it will not ever provide network access, but it can be made to look "built-in"...
Mac App Store access with NullEthernet.kext
On a whim, I created NullEthernet.kext to solve this problem. It is a "fake" Ethernet kext that will never actually work. That is, it will not ever provide network access, but it can be made to look "built-in"...
Mac App Store access with NullEthernet.kext